Thermal controller for electric motors and the like



Mar. 6,' 1923. 1,447,194,, 9 J. R. wane. I

THERMAL CONTROLLER FOR ELECTRIC MOTORS AND THE LIKE. I I

FILED IULY 3.1919.

I cuit through the magnet M, which is so Patented Mar. 6, 1923.

J'OSEI 'H ROGER WHITE, OF WASHINGTON, .DIQIBICT OF COLUMBIA.

THERMAL CONTROLLER FOR ELECTRIC MOTORS AND THE LIKE.

Application filed July 3, 191a Serial No. aoa,ae1.

To all whom it may concern Be it known that I, JOSEPH Room Wmrn, a citizen of the United States, and resident of Washington, in the District of Columbia, have invented certain new and useful Improvements in ThermalControllers for ElectricMotors and'the like, of which the following is a specification, reference. being had therein to the accompanying drawing.

The object of this invention 1s to provide automatic means whereby connecting a motor or thelike with a main electric line will cause a gradually increasing current to ass to the motor until a maximum is reac ed and will thereafter maintain the current until the connection is broken, when the arts will return-to initial position ready or a repetition of the operation.

n the accompanying drawings, which are lar ely diagrammatic,

igure 1 shows my devices arranged in a motor circuit having a swltch connection with a main orpower line.

Figure 2 is a detail showing the means for. heatin r a thermostatic bar.

In t ese ,views, A represents a switch for connecting the motor circuit with a main line B, C a'motor in a circuit rovided with variable resistance at D. is any suitable support for an insulated thermostatic bar F of brass and steel or other suitable metals, and for a flexible resilient bronze bar G in path in which the bar F swings when heated and provided with a soft iron block or armature H. Along one face of the bar F runs a serpentine insulated heating conductor I connecting a circuit wire J to a shoe K adapted to move over contacts L and suc-' cessively cut out resistances.

When the switch A is closed, the member I heats the bar F and the unequal expansion of the two metals causes its flexure carrying the shoe over the contacts. L. In so moving, the bar strikes and carries with it the bar G, until the armature H meets an electro-magnet M and the bar at the same time makes contact at N and completes cirmade as to afl'ord small resistance in comparison with the member I. Practically the entire current now flows through the bronze bar, and so the bar F cools and returns to initial )osition leaving the resilient bronze bar in t e position shown in dotted lines. If at any time the switch A be opened the bronze bar is instantly released by the magnet and by its resiliency removes the armaturgI from the magnet and breaks the contact at The thermostatic device is not necessarily a nearly straight bar, various other forms belng well known and adapted to secure the .same result in substantially the same way.

Obviously'the device avoids in a very simple way well-known evils.

What I claim is:

1. In combination, an electric circuit including a variable resistance, a thermostat havin its" heating element also included in said circuit and its heated member arranged to reduce said resistance progressivel as its own temperature rises, a conductor eading from the circuit line on one side of said resistance and element and in position to be moved by said member, a terminal, connect ed to the line on the opposite side of said resistance and element, in the path of said conductor, the two on' meeting closing a short circuit around said resistance and element, and means for maintaining the short circuit so long as the line circuit is closed.

2. In an electric circuit, a resistance to be cut out, a thermostatic bar provided with a heating conductor and arranged to cut out said resistance progressively, a member actuated by the thermostatic bar for short circuiting 'said conductor and the resistance,

and means for maintaining the member in short circuiting position w n that position is reached. a

3. In an electric circuit, the. combination of resistance to be progressively cut out, a thermostatic bar arranged to be heated by the current and to cut out the resistance progressively, a member moved by the thermostatic bar to position for short circuiting the bar heating current when the resistance has been cut out, and an electromagnet for maintaining the short circuit.

4. The combination with an electrical circuit including a series of resistances to be cut out successively by a moving member, of a thermostatic bar carrying said member, a heating conductor carried by said bar, an electromagnet, a conductor moved by said member in such cutting out to make circuit through the magnet and short circuit the heating conductor.

In testimony whereof I hereunto afiix my signature.

JOSEPH ROGER WHITE. 

